In medical diagnostics, body fluid analysis is routinely performed to qualitatively and/or quantitatively detect one or more analytes therein. In view of the obtained analyte concentration, a physician then makes decisions regarding a potential treatment of the person from whom the body fluid sample was taken.
Typically, test elements are used for detecting an analyte of interest and can be in a form such as test strips that include one or more test fields having one or more test chemistries. The test chemistries are adapted to change one or more detectable properties in the presence of the analyte to be detected. Thus, electrochemically detectable properties of the test chemistry and/or optically detectable properties of the test chemistry may be changed due to the presence of the analyte. For potential test chemistries that may be used within the present disclosure, reference may be made to Hönes et al. (2008) Diabetes Technol. Ther. 10(Supp. 1):S10-S26; and Int'l Patent Application Publication Nos. WO 2010/094426 and WO 2010/094427. However, other types of test chemistries may be used within the present disclosure.
Many different types of test elements having test chemistries are known. For example, EP Patent Application Publication No. 0 302 287 describes a test element for detecting an analyte in blood by using reagents included in a test carrier. The test carrier includes a frame of a plastic material and a multi-layer test field mounted inside the frame.
EP Patent Application Publication No. 0 547 710 describes a cartridge-free stack of test elements. The test elements are not housed in a cartridge and are temporarily and non-destructively fused together so that the stack can be used without a need for a cartridge.
EP Patent Application Publication No. 1 593 434 describes a method of manufacturing an analytical band for liquid samples, specifically for body fluids. In the method, a multiplicity of test fields are manufactured in the form of test labels that then are glued to a transport tape.
EP Patent Application Publication No. 0 821 234 describes a diagnostic test element for determining an analyte concentration or presence in blood. The test element includes a reagent system including a color-forming reagent and a test field having a sample application side and a detection side. The test field is designed so that erythrocytes are prevented from reaching the detection side. The test element also can include a positioning hole to position the test strip inside a diagnostic testing device.
As with test elements, many testing devices are commercially available. A large number of testing devices and systems are known that use test elements in the form of test strips. For example, applications are known in which a multiplicity of test strips are provided by a magazine, where one test strip from the magazine automatically may be provided to the testing device. Other applications, however, are known in which single test strips are used and are inserted into the testing device manually by a user.
Typically, one end of the test strip is adapted to be inserted into the testing device and for detecting the analyte, while the opposing end of the test strip serves as a handle enabling the user to push the test strip into the testing device or to pull the test strip from the testing device.
For applying the sample to the test element, typical test elements therefore provide at least one sample application site, such as a capillary opening in capillary test elements or a sprite net in optical test elements having a top dosing system. Test elements of this type are commercially available, for example, under the trade name Accu-Chek® Active.
In such test elements, the opposing ends intentionally are designed asymmetrically so that the user may readily identify the end of the test element to be inserted into the testing device and a correct orientation for insertion. Typically, the test field is located closer to the front end of the test element, which is inserted into the testing device, whereas the longer end of the test element may be used as a “handle” to enable the user to push or pull it.
Unfortunately in the field of home monitoring performed by elderly persons, children or disabled persons, confusion about the orientation of the test strip often occurs. For example, the user unintentionally may introduce the long end of the test strip rather than the end having the test field into the testing device and/or may introduce the test element into the testing device with the backside facing in an upward direction. Consequently, each test element typically provides at least four different orientations, whereof three orientations are incorrect and only one orientation is a correct measurement orientation.
A test system is needed that is capable of detecting an incorrect insertion of the test element and, preferably, that brings the incorrectly inserted test element to the user's intention. These requirements, however, imply a significant technical effort with regard to testing devices for detecting the incorrect insertion and/or for processing the information regarding the incorrect insertion and for implementing appropriate process steps, such as an output of warnings to the user.
For the foregoing reasons, there is a need for improved test element designs that reduce the technical effort for detecting incorrect insertions of the test elements and, still, provide a high degree of protection against unintentional malfunctions of the test system due to an incorrect insertion of the test element.